Ophthalmic observation apparatus, method for controlling the same, and recording medium

ABSTRACT

An ophthalmic observation apparatus of an embodiment example includes a moving image generating unit, a movement mechanism, an analyzing processor, and a first controller. The moving image generating unit is configured to generate a moving image by illuminating and photographing the subject&#39;s eye. The movement mechanism is configured to move the moving image generating unit. The analyzing processor is configured to sequentially analyze a plurality of still images included in the moving image generated by the moving image generating unit being moved by the movement mechanism to sequentially detect images of a predetermined site of the subject&#39;s eye. The first controller is configured to control the movement mechanism based on a change in a predetermined image parameter of the images sequentially detected by the analyzing processor.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority to U.S. Provisional PatentApplication Ser. No. 63/106,087, filed Oct. 27, 2020, entitled“APPARATUS AND METHOD FOR OPHTHALMIC OBSERVATION”, the entirety of whichis incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates generally to an ophthalmic observationapparatus, a method of controlling the same, a program, and a recordingmedium.

BACKGROUND OF THE INVENTION

An ophthalmic observation apparatus is an apparatus for observing an eyeof a patient (which will be referred to as a subject's eye hereinafter).Ophthalmic observation is conducted to grasp the condition of thesubject's eye in various situations such as examination, surgery, andtreatment.

Conventional ophthalmic observation apparatuses are configured toprovide a user with a magnified image formed by an objective lens, avariable magnification optical system, etc. via an eyepiece. In recentyears, some ophthalmic observation apparatuses are configured tophotograph a magnified image formed by an objective lens, a variablemagnification optical system, etc. with an image sensor, and display thephotographed image obtained (such an ophthalmic observation apparatuswill be referred to as a digital ophthalmic observation apparatus).Examples of such digital ophthalmic observation apparatuses includesurgical microscopes, slit lamp microscopes, and fundus cameras (retinalcameras). In addition, various kinds of ophthalmic examinationapparatuses such as refractometers, keratometers, tonometers, specularmicroscopes, wavefront analyzers, and microperimeters are also providedwith the function of the digital ophthalmic observation apparatus.

Furthermore, some ophthalmic observation apparatuses of recent years useoptical scanning (scanning-type ophthalmic observation apparatus).Examples of such ophthalmic observation apparatuses include scanninglaser ophthalmoscopes (SLOs), and optical coherence tomography (OCT)apparatuses.

Generally, an ophthalmic observation apparatus is configured to providea moving image of a subject's eye to a user (e.g., a health professional(health care practitioner) such as a doctor). A typical digitalophthalmic observation apparatus is configured to perform photographingof a moving image using infrared light and/or visible light asillumination light, and real-time display of the moving image obtainedby the moving image photography. On the other hand, a typicalscanning-type ophthalmic observation apparatus is configured to performdata collection (data acquisition) by repetitive optical scanning,real-time image reconstruction based on datasets sequentially collected,and real-time moving image display of images sequentially reconstructed.The real-time moving image provided in these ways is referred to as anobservation image or a live image.

There are various methods or techniques of observing a subject's eye. Amethod or technique of observing a subject's eye is referred to as anobservation mode. For example, Patent Document 1 below discloses anapparatus configured to be capable of performing selective applicationof various observation modes with individually different conditions suchas illumination angles, magnifications, and light amounts. Further,Patent Document 2 below discloses an apparatus configured to be capableof linking an operation of changing an illumination angle and anoperation of changing a light amount.

One of well-known observation modes is coaxial illumination (alsoreferred to as 0-degree illumination). Coaxial illumination is anobservation mode in which illumination light is projected onto thesubject's eye along the optical axis (or along a direction that isslightly oblique with respect to the optical axis) of the observationoptical system (or the photography optical system). Coaxial illuminationis used to obtain a red reflex image (transillumination image) formed byutilizing diffuse reflection from eye fundus. A red reflex image istypically used for observation of opacity of ocular media (optic media)(e.g., crystalline lens, vitreous body, etc.), observation of thearrangement of an intraocular lens, and so forth.

PRIOR ART DOCUMENTS Patent Documents

-   PATENT DOCUMENT 1: Japanese Unexamined Patent Application    Publication No. 2003-310556-   PATENT DOCUMENT 2: Japanese Unexamined Patent Application    Publication No. 2009-118955

BRIEF SUMMARY OF THE INVENTION Problem to be Solved by the Invention

In coaxial illumination, the area in which fundus reflection of theillumination light returns to the optical system is limited, whichrequires adjusting the position of the optical system so that a widerarea can be observed more brightly. According to conventionaltechnology, position adjustments of the optical system have beenperformed manually and therefore, the search for the optimum position ofthe optical system has been time consuming and labor intensive. Inaddition, there has existed no means to ascertain whether the optimumposition has been actually achieved. For example, even if the opticalsystem has been guided to a position considered optimal by manualoperation, there still has remained a possibility that a preferableposition has existed, but there has been no way of knowing this. Notethat surgery can be performed if the optical system is located at asuitable position to some extent. However, there is room for improvementwhen the following issues are taken into consideration: improvement inthe success rate of surgery; shortening of time required for surgery;decrease in the difficulty of surgery; and reduction in illuminationlight amount. Note also that the same problem arises even in the casewhere an illumination method other than coaxial illumination is employedbecause of the fact that the state and condition of observed imagestypically depend on the position of the optical system.

One object of the present disclosure is to provide a novel method ortechnique for facilitating ophthalmic observation.

Means for Solving the Problem

Some aspect examples are an ophthalmic observation apparatus forobserving a subject's eye that includes: a moving image generating unitconfigured to generate a moving image by illuminating and photographingthe subject's eye; a movement mechanism configured to move the movingimage generating unit; an analyzing processor configured to sequentiallyanalyze a plurality of still images included in the moving imagegenerated by the moving image generating unit being moved by themovement mechanism to sequentially detect images of a predetermined siteof the subject's eye; and a first controller configured to control themovement mechanism based on a change in a predetermined image parameterof the images sequentially detected by the analyzing processor.

In the ophthalmic observation apparatus of some aspect examples, thefirst controller may be configured to control the movement mechanism tostop movement of the moving image generating unit when the imageparameter of the images sequentially detected by the analyzing processorsatisfies a first condition.

In the ophthalmic observation apparatus of some aspect examples, theimage parameter may include brightness, and the first condition mayinclude at least one of a condition that the brightness is maximum and acondition that the brightness is equal to or larger than a firstthreshold value.

In the ophthalmic observation apparatus of some aspect examples, thefirst controller may be configured to control the movement mechanism tostart movement of the moving image generating unit when the imageparameter of the images sequentially detected by the analyzing processorsatisfies a second condition.

In the ophthalmic observation apparatus of some aspect examples, theimage parameter may include brightness, and the second condition mayinclude a condition that the brightness is smaller than a secondthreshold value.

In the ophthalmic observation apparatus of some aspect examples, thefirst controller may be configured to determine a movement direction ofthe moving image generating unit based on the change in the imageparameter and perform a control of the movement mechanism based on themovement direction determined.

In the ophthalmic observation apparatus of some aspect examples, themoving image generating unit may be configured to generate a movingimage of an anterior eye segment of the subject's eye, and thepredetermined site may include a pupil.

In the ophthalmic observation apparatus of some aspect examples, themoving image generating unit may be configured to generate a movingimage of a posterior eye segment of the subject's eye, and thepredetermined site may include an optic nerve head.

In the ophthalmic observation apparatus of some aspect examples, thecontrol of the movement mechanism based on the change in the imageparameter performed by the first controller may be activated andinactivated.

The ophthalmic observation apparatus of some aspect examples may furtherinclude an informing unit configured to perform informing when the imageparameter of the images sequentially detected by the analyzing processorsatisfies a third condition.

The ophthalmic observation apparatus of some aspect examples may furtherinclude a response receiving unit configured to receive a response ofthe user to the informing, wherein the first controller may beconfigured to perform a control of the movement mechanism based on theresponse received by the response receiving unit.

The ophthalmic observation apparatus of some aspect examples may furtherinclude a determining processor configured to perform determination ofwhether or not to perform the control of the movement mechanism based onthe change in the image parameter performed by the first controller.

In the ophthalmic observation apparatus of some aspect examples, thedetermining processor may be configured to perform the determinationbased on the moving image generated by the moving image generating unit.

In the ophthalmic observation apparatus of some aspect examples, thedetermining processor may be configured to determine whether or not atreatment on the subject's eye is being performed based on the movingimage generated by the moving image generating unit, and determine notto perform the control of the movement mechanism when it is determinedthat the treatment is being performed.

The ophthalmic observation apparatus of some aspect examples may furtherinclude a second controller configured to perform at least one ofinforming, increasing in an illumination light amount by the movingimage generating unit, increasing in a gain of an image sensor of themoving image generating unit, and changing of a determination conditionregarding the image parameter when an optimum value of the imageparameter acquired during the control of the movement mechanism based onthe change in the image parameter satisfies a fourth condition.

The ophthalmic observation apparatus of some aspect examples may furtherinclude a third controller configured to decrease an illumination lightamount by the moving image generating unit on condition that the imageparameter is included in a predetermined range after the control of themovement mechanism based on the change in the image parameter.

In the ophthalmic observation apparatus of some aspect examples, theimage parameter may include at least one of brightness, contrast,sharpness, and color tone.

Some aspect examples are a method of controlling an ophthalmicobservation apparatus including an optical system for observing asubject's eye and a processor, the method including: causing theophthalmic observation apparatus to perform movement of the opticalsystem and generation of a moving image of the subject's eye by theoptical system in parallel; causing the processor to sequentiallyanalyze a plurality of still images included in the moving image tosequentially detect images of a predetermined site of the subject's eye;and causing the processor to perform movement of the optical systembased on a change in a predetermined image parameter of the imagessequentially detected.

Some aspect examples are a program configured to cause a computer toexecute the method of some aspect examples.

Some aspect examples are a computer-readable non-transitory recordingmedium storing the program of some aspect examples.

Effect of the Invention

These aspect examples allow ophthalmic observation to be facilitated.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

FIG. 1 is a diagram illustrating an example of a configuration of anophthalmic observation apparatus (ophthalmic surgical microscope)according to an embodiment example.

FIG. 2 is a diagram illustrating an example of a configuration of anophthalmic observation apparatus according to an embodiment example.

FIG. 3 is a diagram illustrating an example of a configuration of anophthalmic observation apparatus according to an embodiment example.

FIG. 4 is a diagram illustrating an example of a configuration of anophthalmic observation apparatus according to an embodiment example.

FIG. 5 is a diagram illustrating an example of a configuration of anophthalmic observation apparatus according to an embodiment example.

FIG. 6 is a flowchart illustrating an example of processing performed byan ophthalmic observation apparatus according to an embodiment example.

FIG. 7A is a diagram for describing an example of processing performedby an ophthalmic observation apparatus according to an embodimentexample.

FIG. 7B is a diagram for describing an example of processing performedby an ophthalmic observation apparatus according to an embodimentexample.

FIG. 7C is a diagram for describing an example of processing performedby an ophthalmic observation apparatus according to an embodimentexample.

DETAILED DESCRIPTION OF THE INVENTION

Some aspect examples of an ophthalmic observation apparatus, a method ofcontrolling the same, a program, and a recording medium according tosome embodiments will be described in detail with reference to thedrawings. It should be noted that any of the matters and items describedin the documents cited in the present disclosure and any knowntechniques and technologies may be combined with any of the aspectexamples.

It should be noted that there exists a conventional technique ortechnology in which an optical system is devised for the purpose ofimproving the illumination performance of an ophthalmic observationapparatus (e.g., the performance of coaxial illumination). Even withproducts to which such a conventional technique or technology is appliedhowever, it is still possible to make a further improvement in theillumination performance by combining the technique or technology of thepresent disclosure.

The ophthalmic observation apparatus according to some aspect examplesis used in medical practice (healthcare practice) such as examination,surgery, and treatment of the subject's eye, in order to grasp(understand, recognize, find) the state of the subject's eye. Theophthalmic observation apparatus of the aspect examples described hereinis mainly a surgical microscope system. However, ophthalmic observationapparatuses of embodiments are not limited to surgical microscopesystems. For example, the ophthalmic observation apparatus of someaspect examples may be any of a slit lamp microscope, a fundus camera, arefractometer, a keratometer, a tonometer, a specular microscope, awavefront analyzer, a microperimeter, an SLO, and an OCT apparatus.Also, the ophthalmic observation apparatus of some aspect examples maybe a system that includes any one or more of these apparatus examples.In a wider sense, the ophthalmic observation apparatus of some aspectexamples may be any type of ophthalmic apparatus having an observationfunction.

A target ocular site for observation (ocular site to be observed, ocularsite subject to observation) by using the ophthalmic observationapparatus may be any site of the subject's eye, and may be any site ofthe anterior eye segment and/or any site of the posterior eye segment.Examples of the observation target sites of the anterior eye segmentinclude cornea, iris, anterior chamber, corner angle, crystalline lens,ciliary body, and zonule of Zinn. Examples of the observation targetsites of the posterior eye segment include retina, choroid, sclera, andvitreous body. The observation target site is not limited to tissues ofan eye ball, and may be any site subject to be observed in ophthalmicmedical practice (and/or medical practice in other medical fields) suchas eyelid, meibomian gland, and orbit (eye socket, eye pit).

At least one or more of the functions of the elements described in thepresent disclosure are implemented by using a circuit configuration (orcircuitry) or a processing circuit configuration (or processingcircuitry). The circuitry or the processing circuitry includes any ofthe followings, all of which are configured and/or programmed to executeat least one or more functions disclosed herein: a general purposeprocessor, a dedicated processor, an integrated circuit, a centralprocessing unit (CPU), a graphics processing unit (GPU), an applicationspecific integrated circuit (ASIC), a programmable logic device (e.g., asimple programmable logic device (SPLD), a complex programmable logicdevice (CPLD), or a field programmable gate array (FPGA)), aconventional circuit configuration or circuitry, and any combination ofthese. A processor is considered to be processing circuitry or circuitrythat includes a transistor and/or another circuitry. In the presentdisclosure, circuitry, a unit, a means, or a term similar to these ishardware that executes at least one or more functions disclosed herein,or hardware that is programmed to execute at least one or more functionsdisclosed herein. Hardware may be the hardware disclosed herein, oralternatively, known hardware that is programmed and/or configured toexecute at least one or more functions described herein. In the casewhere the hardware is a processor, which may be considered as a certaintype of circuitry, then circuitry, a unit, a means, or a term similar tothese is a combination of hardware and software. In this case, thesoftware is used to configure the hardware and/or the processor.

<Ophthalmic Observation Apparatus>

FIG. 1 shows the configuration of the ophthalmic observation apparatusof some aspect examples.

The ophthalmic observation apparatus 1 (surgical microscope system,operation microscope system) according to the present embodimentincludes the operation device 2, the display device 3, and the surgicalmicroscope (operation microscope) 10. In some aspects, the surgicalmicroscope 10 may include at least one of the operation device 2 and thedisplay device 3. In some aspects, the display device 3 may not beincluded in the ophthalmic observation apparatus 1. In other words, thedisplay device 3 may be a peripheral device of the ophthalmicobservation apparatus 1.

<Operation Device 2>

The operation device 2 includes an operation device and/or an inputdevice. For example, the operation device 2 may include any of a button,a switch, a mouse, a keyboard, a trackball, an operation panel, a dial,and so forth. Typically, the operation device 2 includes a foot switch,like standard (general, normal, usual) ophthalmic surgical microscopes.Further, the operation device 2 may also be configured in such a mannerthat the user performs operations using voice recognition, line-of-sight(gaze) input, or like input technologies.

<Display Device 3>

The display device 3 displays an image of the subject's eye acquired bythe surgical microscope 10. The display device 3 includes a displaydevice such as a flat panel display. The display device 3 may includeany of various kinds of display devices such as a touch panel. Thedisplay device 3 of some typical aspects includes a display device witha large screen. The display device 3 includes one or more displaydevices. In the case where the display device 3 includes two or moredisplay devices, for example, one may be a display device with arelatively large screen and one of the other(s) may be a display devicewith a relatively small screen. Also, a configuration may be employed inwhich a plurality of display regions is provided in one display deviceto display a plurality of pieces of information.

The operation device 2 and the display device 3 do not have to beseparate devices. For example, a device having both the operationfunction and the display function, such as a touch panel, may be used asthe display device 3. In such a case, the operation device 2 may includea computer program in addition to the touch panel. A content of anoperation made by the operation device 2 is sent to a processor (notshown in the drawings) as an electric signal. Further, a graphical userinterface (GUI) displayed on the display device 3 and the operationdevice 2 may be used to conduct operations (instructions) and inputinformation. In some aspects, the functions of the operation device 2and the display device 3 may be implemented with a touch screen.

<Surgical Microscope 10>

The surgical microscope 10 is used for observation of the eye of apatient (subject's eye) in the supine position. The surgical microscope10 performs photographing of the subject's eye to generate digital imagedata. In particular, the surgical microscope 10 generates a moving imageof the subject's eye. The moving image (video, movie) generated by thesurgical microscope 10 is transmitted to the display device 3 through awired and/or wireless signal path and displayed on the display device 3.The user (e.g., surgeon) can carry out surgery while observing thesubject's eye through the displayed image. In addition to suchobservation through the displayed image, the surgical microscope 10 ofsome aspects may also be capable of providing observation through aneyepiece as in conventional technology.

In some aspects, the surgical microscope 10 includes a communicationdevice for transmitting and receiving electrical signals to and from theoperation device 2. The operation device 2 receives an operation(instruction) performed by the user and generates an electric signal(operation signal) corresponding to the operation. The operation signalis transmitted to the surgical microscope 10 through a wired and/orwireless signal path. The surgical microscope 10 executes processingcorresponding to the operation signal received.

<Optical System of Surgical Microscope 10>

An example of the configuration of the optical system of the surgicalmicroscope 10 will be described. Below, directions are defined asfollows, for convenience of description: the z direction is defined tobe the optical axis direction (direction along the optical axis) of theobjective lens (the z direction is, for example, the vertical direction,the up and down direction during surgery); the x direction is defined tobe a predetermined direction perpendicular to the z direction (the xdirection is, for example, the horizontal direction during surgery, andthe left and right direction for the surgeon and the patient duringsurgery); and the y direction is defined to be the directionperpendicular to both the z and x directions (the y direction is, forexample, the horizontal direction during surgery, the front and backdirection for the surgeon during surgery, and the body axis direction(direction along the body axis) for the patient during surgery).

In addition, the case where the observation optical system includes apair of left and right optical systems (optical systems capable ofbinocular observation) will be mainly described below. However, anobservation optical system of some other aspects may have an opticalsystem for monocular observation, and it will be understood by thoseskilled in the art that the configuration described below may beincorporated into the aspects for monocular observation.

FIG. 2 shows an example of the configuration of the optical system ofthe surgical microscope 10. FIG. 2 illustrates a schematic top view ofthe optical system viewed from above (top view) and a schematic sideview of the optical system viewed from the side (side view) inassociation with each other. In order to simplify the illustration, theillumination optical system 30 arranged above the objective lens 20 isomitted in the top view.

The surgical microscope 10 includes the objective lens 20, the dichroicmirror DM1, the illumination optical system 30, and the observationoptical system 40. The observation optical system 40 includes the zoomexpander 50, and the imaging camera 60. In some aspects, theillumination optical system 30 or the observation optical system 40includes the dichroic mirror DM1.

The objective lens 20 is arranged to face the subject's eye. Theobjective lens 20 is arranged such that its optical axis is orientedalong the z direction. The objective lens 20 may include two or morelenses.

The dichroic mirror DM1 couples the optical path of the illuminationoptical system 30 and the optical path of the observation optical system40 with each other. The dichroic mirror DM1 is arranged between theillumination optical system 30 and the objective lens 20. The dichroicmirror DM1 transmits illumination light from the illumination opticalsystem 30 and directs the illumination light to the subject's eyethrough the objective lens 20. Also, the dichroic mirror DM1 reflectsreturn light from the subject's eye incident through the objective lens20 and directs the return light to the imaging camera 60 of theobservation optical system 40.

The dichroic mirror DM1 coaxially couples the optical path of theillumination optical system 30 and the optical path of the observationoptical system 40 with each other. In other words, the optical axis ofthe illumination optical system 30 and the optical axis of theobservation optical system 40 intersect at the dichroic mirror DM1. Inthe case where the illumination optical system 30 includes anillumination optical system for left eye (31L) and an illuminationoptical system for right eye (31R) and where the observation opticalsystem 40 includes an observation optical system for left eye 40L and anobservation optical system for right eye 40R, the dichroic mirror DM1coaxially couples the optical path of the illumination optical systemfor left eye (the first illumination optical system 31L) and the opticalpath of the observation optical system for left eye 40L with each other,and coaxially couples the optical path of the illumination opticalsystem for right eye (the first illumination optical system 31R) and theoptical path of the observation optical system for right eye 40R witheach other.

The illumination optical system 30 is an optical system for illuminatingthe subject's eye through the objective lens 20. The illuminationoptical system 30 may be configured to selectively illuminate thesubject's eye with two or more pieces of illumination light havingdifferent color temperatures. The illumination optical system 30projects illumination light having a designated color temperature ontothe subject's eye under the control of a controller (the controller 200described later).

The illumination optical system 30 includes the first illuminationoptical systems 31L and 31R and the second illumination optical system32.

Each of the optical axis OL of the first illumination optical system 31Land the optical axis OR of the first illumination optical system 31R isarranged with the optical axis of the objective lens 20 in asubstantially coaxial manner. Such arrangements enable a coaxialillumination mode and therefore make it possible to obtain a red refleximage (transillumination image) formed by utilizing diffuse reflectionfrom eye fundus. The present aspect allows the red reflex image of thesubject's eye to be observed with both eyes.

The second illumination optical system 32 is arranged in such a mannerthat its optical axis OS is eccentric (deviated, shifted) from theoptical axis of the objective lens 20. The first illumination opticalsystems 31L and 31R and the second illumination optical system 32 arearranged such that the deviation of the optical axis OS with respect tothe optical axis of the objective lens 20 is larger than the deviationsof the optical axes OL and OR with respect to the optical axis of theobjective lens 20. Such arrangements enable an illumination modereferred to as “angled illumination (oblique illumination)” andtherefore enables binocular observation of the subject's eye whilepreventing ghosting caused by corneal reflection or the like. Inaddition, the arrangements enable detailed observation of unevenness andirregularities of sites and tissues of the subject's eye.

The first illumination optical system 31L includes the light source 31LAand the condenser lens 31LB. The light source 31LA outputs illuminationlight having a wavelength in the visible range (visible region)corresponding to color temperature of 3000 K (kelvins), for example. Theillumination light emitted from the light source 31LA passes through thecondenser lens 31LB, passes through the dichroic mirror DM1, passesthrough the objective lens 20, and then is incident on the subject'seye.

The first illumination optical system 31R includes the light source 31RAand the condenser lens 31RB. The light source 31RA also outputsillumination light having a wavelength in the visible rangecorresponding to color temperature of 3000 K, for example. Theillumination light emitted from the light source 31RA passes through thecondenser lens 31RB, passes through the dichroic mirror DM1, passesthrough the objective lens 20, and then is incident on the subject'seye.

The second illumination optical system 32 includes the light source 32Aand the condenser lens 32B. The light source 32A outputs illuminationlight having a wavelength in the visible range corresponding to a colortemperature within the range of 4000 K to 6000 K, for example. Theillumination light emitted from the light source 32A passes through thecondenser lens 32B, passes through the objective lens 20 without passingthrough the dichroic mirror DM1, and then is incident on the subject'seye.

In the present aspect example, the color temperature of the illuminationlight from the first illumination optical systems 31L and 31R is lowerthan the color temperature of the illumination light from the secondillumination optical system 32. Such a configuration makes it possibleto observe the subject's eye in warm colors using the first illuminationoptical systems 31L and 31R, and therefore enables detailed observationof the structure and morphology of the subject's eye.

In some aspects, each of the optical axes OL and OR is movable relativeto the optical axis of the objective lens 20. The direction of therelative movement is a direction that intersects the optical axis of theobjective lens 20, and the relative movement is represented by adisplacement vector in which at least one of the x component and the ycomponent is not zero. In some aspects, the optical axes OL and OR maybe mutually independently movable. On the other hand, in some aspects,the optical axes OL and OR may be integrally movable. For example, thesurgical microscope 10 includes a movement mechanism (31 d) configuredto move the first illumination optical systems 31L and 31R mutuallyindependently or integrally, and therefore the movement mechanism movesthe first illumination optical systems 31L and 31R mutuallyindependently or integrally in a direction intersecting the optical axisof the objective lens 20. Such a configuration makes it possible toconduct adjustment of the appearance condition (appearance state) of thesubject's eye. In some aspects, the movement mechanism operates underthe control of a controller (the controller 200 described later).

In some aspects, the optical axis OS is movable relative to the opticalaxis of the objective lens 20. The direction of the relative movement isa direction that intersects the optical axis of the objective lens 20,and the relative movement is represented by a displacement vector inwhich at least one of the x component and the y component is not zero.For example, the surgical microscope 10 includes a movement mechanism(32 d) configured to move the second illumination optical system 32, andtherefore the movement mechanism moves the second illumination opticalsystem 32 in a direction that intersects the optical axis of theobjective lens 20. With such a configuration, it becomes possible toconduct adjustment of the appearance condition (appearance state) ofunevenness and irregularities of sites and tissues of the subject's eye.In some aspects, the movement mechanism operates under the control of acontroller (the controller 200 described later).

As described above, the present aspect is configured such that theillumination optical system 30 is arranged at the position directlyabove the objective lens 20 (the position in the transmission directionof the dichroic mirror DM1) and the observation optical system 40 isarranged at the position in the reflection direction of the dichroicmirror DM1. For example, the observation optical system 40 may bearranged in such a manner that the angle formed by the optical axis ofthe observation optical system 40 and the plane perpendicular to theoptical axis of the objective lens 20 (the xy plane) belongs to therange between −20 degrees and +20 degrees.

According to the configuration of the present aspect, the observationoptical system 40, which typically has a longer optical path length thanthe illumination optical system 30, is arranged substantially parallelto the xy plane. Hence, the observation optical system 40 of the presentaspect does not interfere with the surgeon's field of view whileconventional surgical microscopes, whose observation optical system isoriented along the vertical direction in front of the surgeon's eyes,do. Therefore, the surgeon is capable of easily seeing the screen of thedisplay device 3 arranged in front of the surgeon. In other words, thevisibility of displayed information (images and videos of the subject'seye, and other various kinds of reference information) during surgeryetc. is improved. In addition, since the housing is not placed in frontof the surgeon's eyes, it does not give a sense of oppression to thesurgeon, thereby reducing the burden on the surgeon.

The observation optical system 40 is an optical system for observationof an image formed based on return light of the illumination lightincident from the subject's eye through the objective lens 20. In thepresent aspect, the observation optical system 40 guides the image to animage sensor of the imaging camera 60.

As described above, the observation optical system 40 includes theobservation optical system for left eye 40L and the observation opticalsystem for right eye 40R. The configuration of the observation opticalsystem for left eye 40L and the configuration of the observation opticalsystem for right eye 40R are the same as or similar to one another. Insome aspects, the observation optical system for left eye 40L and theobservation optical system for right eye 40R may be configured in such amanner that their optical arrangements can be changed independently ofeach other.

The zoom expander 50 is also referred to as a beam expander, a variablebeam expander, or the like. The zoom expander 50 includes the zoomexpander for left eye 50L and the zoom expander for right eye 50R. Theconfiguration of the zoom expander for left eye 50L and theconfiguration of the zoom expander for right eye 50R are the same as orsimilar to each other. In some aspects, the zoom expander for left eye50L and the zoom expander for right eye 50R may be configured in such amanner that their optical arrangements can be changed independently ofeach other.

The zoom expander for left eye 50L includes the plurality of zoom lenses51L, 52L, and 53L. At least one of the zoom lenses 51L, 52L, and 53L ismovable in the direction along the optical axis with a variablemagnification mechanism (not shown in the drawings).

Similarly, the zoom expander for right eye 50R includes the plurality ofzoom lenses 51R, 52R, and 53R, and at least one of the zoom lenses 51R,52R, and 53R is movable in the direction along the optical axis with avariable magnification mechanism (not shown in the drawings).

The variable magnification mechanism(s) may be configured to move a zoomlens of the zoom expander for left eye 50L and a zoom lens of the zoomexpander for right eye 50R mutually independently or integrally in thedirections along the optical axes. As a result of this, themagnification ratio for photographing the subject's eye is changed. Insome aspects, the variable magnification mechanism(s) operates under thecontrol of a controller (the controller 200 described later).

The imaging camera 60 is a device that photographs an image formed bythe observation optical system 40 and generates digital image data. Theimaging camera 60 is typically a digital camera (digital video camera).The imaging camera 60 includes the imaging camera for left eye 60L andthe imaging camera for right eye 60R. The configuration of the imagingcamera for left eye 60L and the configuration of the imaging camera forright eye 60R are the same as or similar to one another. In someaspects, the imaging camera for left eye 60L and the imaging camera forright eye 60R may be configured such that their optical arrangements canbe changed independently of each other.

The imaging camera for left eye 60L includes the imaging lens 61L andthe image sensor 62L. The imaging lens 61L forms an image based on thereturn light that has passed through the zoom expander for left eye 50L,on the imaging surface (light receiving surface) of the image sensor62L. The image sensor 62L is an area sensor, and may typically be acharge-coupled device (CCD) image sensor or a complementary metal oxidesemiconductor (CMOS) image sensor. The image sensor 62L operates underthe control of a controller (the controller 200 described later).

The imaging camera for right eye 60R includes the imaging lens 61R andthe image sensor 62R. The imaging lens 61R forms an image based on thereturn light that has passed through the zoom expander for right eye50R, on the imaging surface (light receiving surface) of the imagesensor 62R. The image sensor 62R is an area sensor, and may typically bea CCD image sensor or a CMOS image sensor. The image sensor 62R operatesunder the control of a controller (the controller 200 described later).

<Processing System>

The processing system of the ophthalmic observation apparatus 1 will bedescribed. Some configuration examples of the processing system areshown in FIG. 3 and FIG. 4 . Any two or more of the plurality ofconfiguration examples described below may be combined at least in part.Note that the configuration of the processing system is not limited tothe examples described below.

The controller 200 executes a control of each part of the ophthalmicobservation apparatus 1. The controller 200 includes the main controller201 and the memory 202. The main controller 201 includes a processor andexecutes a control of each part of the ophthalmic observation apparatus1. For example, the processor may load and run a program stored in thememory 202 or another storage device, thereby implementing a functionaccording to the present aspect. In addition, the processor may use(e.g., referring, processing, calculating, etc.) data and/or informationstored in the memory 202 or another storage device in order to implementa function according to the present aspect.

The main controller 201 may control the light sources 31LA, 31RA, and32A of the illumination optical system 30, the image sensors 62L and 62Rof the observation optical system 40, the movement mechanisms 31 d and32 d, the variable magnification mechanisms 50Ld and 50Rd, the operationdevice 2, the display device 3, and other component parts.

Controls of the light source 31LA include turning on and off the lightsource, adjusting the light amount, adjusting the diaphragm (aperture),and so forth. Controls of the light source 31RA include turning on andoff the light source, adjusting the light amount, adjusting thediaphragm (aperture), and so forth. The main controller 201 may performmutually exclusive controls of the light sources 31LA and 31RA. Controlsof the light source 32A include turning on and off the light source,adjusting the light amount, adjusting the diaphragm (aperture), and soforth.

In the case where the illumination optical system 30 includes a lightsource whose color temperature can be varied, the main controller 201may change the color temperature of emitted illumination light bycontrolling such a light source.

Controls of the image sensor 62L include exposure adjustment, gainadjustment, photographing rate adjustment, and so forth. Controls of theimage sensor 62R include exposure adjustment, gain adjustment,photographing rate adjustment, and so forth. Further, the maincontroller 201 may control the image sensors 62L and 62R in such amanner that the photographing timings of the image sensors 62L and 62Rmatch each other, or in such a manner that the difference between thephotographing timings of the image sensors 62L and 62R lies within apredetermined time. In addition, the main controller 201 may perform acontrol of loading digital data obtained by the image sensors 62L and62R.

The movement mechanism 31 d moves the light sources 31LA and 31RAmutually independently or integrally in a direction that intersects theoptical axis of the objective lens 20. By controlling the movementmechanism 31 d, the main controller 201 moves the optical axes OL and ORmutually independently or integrally with respect to the optical axis ofthe objective lens 20.

The movement mechanism 32 d moves the light source 32A in a directionthat intersects the optical axis of the objective lens 20. Bycontrolling the movement mechanism 32 d, the main controller 201 movesthe optical axis OS with respect to the optical axis of the objectivelens 20.

The movement mechanism 70 moves the surgical microscope 10. For example,the movement mechanism 70 is configured to integrally move at least partof the illumination optical system 30 and the observation optical system40. This configuration makes it possible to change the relativepositions of the at least part of the illumination optical system 30 andthe observation optical system 40 with respect to the subject's eyewhile maintaining the relative positional relationship between at leastpart of the illumination optical system 30 and the observation opticalsystem 40. In some aspects, the movement mechanism 70 is configured tointegrally move the first illumination optical systems 31L and 31R andthe observation optical system 40. With this, the relative positions ofthe first illumination optical systems 31L and 31R with respect to thesubject's eye and the relative position of the observation opticalsystem 40 with respect to the subject's eye can be changed whilemaintaining the state (condition) of coaxial illumination. In someaspects, the movement mechanism 70 is configured to integrally move thesecond illumination optical system 32 and the observation optical system40. With this, the relative positions of the second illumination opticalsystem 32 and the observation optical system 40 with respect to thesubject's eye can be changed while maintaining the illumination anglefor oblique illumination. In some aspects, the movement mechanism 70 isconfigured to integrally move the first illumination optical systems 31Land 31R, the second illumination optical system 32, and the observationoptical system 40. This makes it possible to change the relativepositions of the illumination optical system 30 and the observationoptical system 40 with respect to the subject's eye while maintainingboth the state (condition) of coaxial illumination and the illuminationangle for oblique illumination. The movement mechanism 70 operates undera control of the controller 200.

In some aspects, the main controller 201 may be configured to control atleast two of the movement mechanisms 31 d, 32 d, and 70 in aninterlocking manner.

The variable magnification mechanism 50Ld moves at least one of theplurality of zoom lenses 51L to 53L of the zoom expander for left eye50L in the optical axis direction (direction along the optical axis).The main controller 201 changes the magnification ratio of theobservation optical system for left eye 40L by controlling the variablemagnification mechanism 50Ld.

Similarly, the variable magnification mechanism 50Rd moves at least oneof the plurality of zoom lenses 51R to 53R of the zoom expander forright eye 50R in the optical axis direction (direction along the opticalaxis). The main controller 201 changes the magnification ratio of theobservation optical system for right eye 40R by controlling the variablemagnification mechanism 50Rd.

Controls for the operation device 2 include an operation permissioncontrol, an operation prohibition control, an operation signaltransmission control and/or an operation signal reception control fromthe operation device 2, and other controls. The main controller 201receives an operation signal generated by the operation device 2 andexecutes a control corresponding to the operation signal received.

Controls for the display device 3 include an information display controland other controls. As a display controller, the main controller 201displays an image based on digital image data generated by the imagesensors 62L and 62R on the display device 3. Typically, the maincontroller 201 may display a moving image (video, movie) based ondigital image data (video signal) generated by the image sensors 62L and62R on the display device 3. Further, the main controller 201 maydisplay a still image (frame) included in the moving image on thedisplay device 3. In addition, the main controller 201 may display animage (a moving image, a still image, etc.) obtained by processing thedigital image data generated by the image sensors 62L and 62R on thedisplay device 3. Furthermore, the main controller 201 may display, onthe display device 3, any information generated by the ophthalmicobservation apparatus 1, any information acquired from the outside bythe ophthalmic observation apparatus 1, and other types of information.

Further, as a display controller, the main controller 201 may create animage for left eye from the digital image data generated by the imagesensor 62L and create an image for right eye from the digital image datagenerated by the image sensor 62R, and then display the created imagefor left eye and the created image for right eye on the display device 3in such a manner as to enable stereoscopic vision. For example, the maincontroller 201 may create a pair of left and right parallax images fromthe image for left eye and the image for right eye, and display the pairof parallax images on the display device 3. With this, the user (e.g.,surgeon) can recognize the pair of parallax images as a stereoscopicimage by using a known stereoscopic method or technique. Thestereoscopic method applicable to the present aspect may be freelyselected, and for example, may be any of the following methods: astereoscopic method for naked eyes; a stereoscopic method using anauxiliary device (polarized glasses, etc.); a stereoscopic method byapplying image processing (image synthesis, image composition,rendering, etc.) to an image for left eye and an image for right eye; astereoscopic method by displaying a pair of parallax imagessimultaneously; a stereoscopic method by alternately displaying a pairof parallax images; and a stereoscopic method of a combination of two ormore of the above methods.

The data processor 210 executes various kinds of data processes. Someexamples of processing that may be executed by the data processor 210will be described below. The data processor 210 (each element thereof)includes a processor that operates on the basis of predeterminedsoftware (program), and is implemented by the cooperation of hardwareand software.

Some examples of processing that may be executed by the data processor210 will be described together with related elements. FIG. 4 shows aconfiguration example of the data processor 210 (and related elementsthereto). The data processor 210A shown in FIG. 4 is an example of thedata processor 210 in FIG. 3 and includes the analyzing processor 211.

The controller 200 of the present aspect may be configured to performthe following controls in parallel which is rereferred to as a parallelcontrol: a control of the movement mechanism 70 to integrally move theillumination optical system 30 and the observation optical system 40,which is referred to as a movement control; and a control of theillumination optical system 30 and the observation optical system 40 toperform moving image photography (including illumination andphotography) of the subject's eye, which is referred to as a photographycontrol. The mode or aspect of the parallel control may be freelydesigned or determined. For example, the parallel control may include asimultaneous execution of the movement control and the photographycontrol (referred to as a simultaneous control), an alternate executionof the movement control and the photography control (referred to as analternate control), or a combination of the simultaneous control and thealternate control.

One or more frames (still images) of a moving image (frame group, stillimage group) acquired by the parallel control performed in this way, areinput into the analyzing processor 211. Here, all the still imagesacquired by the parallel control may be input into the analyzingprocessor 211, or only still images selected by thinning or likeprocessing may be input into the analyzing processor 211. In the lattercase, for example, the still image selection processing is executed bythe controller 200 or the data processor 210A. It should be noted thatin the former case, the analyzing processor 211 may perform the stillimage selection processing. In the present aspect, the parallel controland processing performed by the analyzing processor 211 are executedboth sequentially and in real time. Therefore, overall processing loadcan be reduced by assigning the still image selection processing to theanalyzing processor 211. Note that the method for reducing processingload is not limited to the still image selection processing. In the casewhere the ophthalmic observation apparatus 1 has sufficient processingresources, no processing load reduction method may be employed.

The analyzing processor 211 is configured to sequentially analyze aplurality of still images included in a moving image generated by thephotography control executed in parallel with the movement control, tosequentially detect images of a predetermined site of the subject's eye.

The site of the subject's eye detected by the analyzing processor 211may be freely selected or determined. In the case where a target site (apart or region of the subject's eye) to be observed by the ophthalmicobservation apparatus 1 is the anterior eye segment, the analyzingprocessor 211 may be configured to detect any of the following sites,for example: the pupil (its entirety, or a feature site such as thepupil edge, the pupil center, or the pupil center of gravity), thecornea (its entirety, or a feature site such as the corneal ring, thecorneal edge, the corneal center, or the corneal apex), the iris (itsentirety, or a feature site such as the iris inner edge, the iris outeredge, or the iris pattern), the anterior chamber (its entirety, or afeature site such as the anterior border, or the posterior border), thecorner angle (its entirety, a peripheral site, etc.), the crystallinelens (its entirety, or a feature site such as the lens capsule, theanterior capsule, the posterior capsule, or the lens nucleus), theciliary body, the zonule of Zinn, a blood vessel, and a lesion. In thecase where a target site to be observed by the ophthalmic observationapparatus 1 is the posterior eye segment, the analyzing processor 211may be configured to detect any of the following sites, for example: theoptic nerve head, the macula, a blood vessel, the retina (its entirety,the surface, or one or more sub-tissues), the choroid (its entirety, theanterior surface, the posterior surface, or one or more sub-tissues),the sclera (its entirety, the anterior surface, the posterior surface,or one or more sub-tissues), the vitreous body (its entirety, an opaqueregion, a floating object (floater), a detached tissue, etc.), and alesion. In the case where a target site to be observed by the ophthalmicobservation apparatus 1 is not a tissue of an eye ball, the analyzingprocessor 211 may be configured to detect a freely selected site ortissue such as the eyelid, the meibomian glands, or the orbit (eyesocket, eye pit). The site to be detected by the analyzing processor 211may be selected or determined depending on an illumination methodemployed, a site subject to surgery, a surgical method conducted, orother factors.

The analyzing processor 211 may be configured to detect an image of apredetermined site of the subject's eye from a still image using afreely selected region extraction method or technique. In some examplesof detecting an image of a site characterized by its brightness (animage of a site that has a distinctive feature in brightness), theanalyzing processor 211 may be configured to perform detection of animage of this site of the subject's eye from a still image usingbrightness thresholding such as binarization. In the case of detectingan image of a site characterized by its shape (an image of a site thathas a distinctive feature in shape), the analyzing processor 211 may beconfigured to perform detection of an image of this site of thesubject's eye from a still image using shape analysis processing such aspattern matching. In the case of detecting an image of a sitecharacterized by its color tone (an image of a site that has adistinctive feature in color tone), the analyzing processor 211 may beconfigured to perform detection of an image of this site of thesubject's eye from a still image using color analysis processing such asfeature color extraction. In some examples, the analyzing processor 211may be configured to detect an image of a predetermined site of thesubject's eye by applying segmentation to a still image to identify animage of this site of the subject's eye. Typically, segmentation isimage processing for identifying a partial region (subregion) in a givenimage. Segmentation may include any known image processing technique,and some examples of which may include image processing such as edgedetection and/or machine learning (e.g., deep learning) basedsegmentation.

The controller 200 (and the data processor 210A) is configured tocontrol the movement mechanism 70 based on a change in a predeterminedimage parameter of the images of the predetermined site sequentiallydetected from the moving image by the analyzing processor 211. Thecontroller 200 (and the data processor 210A) that performs this controlcorresponds to the first controller. The movement direction of theillumination optical system 30 and the observation optical system 40moved by this control of the movement mechanism 70 may be freelyselected or determined. For example, the movement direction may be anyone or more of the vertical direction (the Z direction), the horizontaldirection (the X direction), and the front and back direction (the Ydirection).

As a result, the ophthalmic observation apparatus 1 becomes capable ofperforming position adjustment of the surgical microscope 10 accordingto a change in the image parameter in response to a change in theposition of the surgical microscope 10 with respect to the subject'seye. For example, as mentioned above, in coaxial illumination, the areain which fundus reflection of the illumination light returns to theoptical system is limited, which requires adjusting the position of theoptical system so that a wider area can be observed more brightly. Sinceconventional technology has required to manually perform positionadjustment of the optical system, the search for an optimum position ofthe optical system has been time consuming and labor intensive. Incontrast, the present aspect is capable of automatically performing thesearch for an optimum position of the optical system while monitoringthe image parameter. Furthermore, the present aspect is capable of, byreferring to the image parameter, ascertaining whether the optimumposition is actually achieved. Thus, according to the present aspect,ophthalmic observation can be facilitated, and also improvements can bemade in various areas such as the success rate of surgery, the durationof time required for surgery, difficulty of surgery, and so forth. Thesame applies to the case where an illumination method other than coaxialillumination, such as angled illumination (oblique illumination), isemployed.

The type or kind of the image parameter taken into consideration by thecontroller 200 (and the data processor 210A) may be freely selected ordetermined. For example, the image parameter may be at least one ofbrightness, contrast, sharpness, and color tone.

The controller 200 (and the data processor 210A) may be configured tocontrol the movement mechanism 70 to stop movement of the illuminationoptical system 30 and the observation optical system 40 under thecondition that the image parameter of the images of the predeterminedsite sequentially detected from the moving image by the analyzingprocessor 211 satisfies the first condition. In some examples, thecontroller 200 (and the data processor 210A) may be configured tocontrol the movement mechanism 70 to stop movement of the illuminationoptical system 30 and the observation optical system 40 when thebrightness (or, contrast or sharpness) of the images of thepredetermined site sequentially detected from the moving image by theanalyzing processor 211 reaches the maximum. In some other examples, thecontroller 200 (and the data processor 210A) may be configured tocontrol the movement mechanism 70 to stop movement of the illuminationoptical system 30 and the observation optical system 40 when thebrightness (or, contrast or sharpness) of the images of thepredetermined site sequentially detected from the moving image by theanalyzing processor 211 reaches or exceeds a predetermined thresholdvalue. In some still other examples, the controller 200 (and the dataprocessor 210A) may be configured to control the movement mechanism 70to stop movement of the illumination optical system 30 and theobservation optical system 40 when the color tone of the images of thepredetermined site sequentially detected from the moving image by theanalyzing processor 211 falls within a predetermined allowable range.The threshold value and the range in the first condition may be fixed orvariable.

As a result of this, the illumination optical system 30 and theobservation optical system 40 can be automatically guided and placed atpositions where a suitable image parameter can be obtained. With this,advantageous effects such as facilitation of ophthalmic observation canbe achieved.

The controller 200 (and the data processor 210A) may be configured tocontrol the movement mechanism 70 to start movement of the illuminationoptical system 30 and the observation optical system 40 under thecondition that the image parameter of the images of the predeterminedsite sequentially detected from the moving image by the analyzingprocessor 211 satisfies the second condition. In some examples, thecontroller 200 (and the data processor 210A) may be configured tocontrol the movement mechanism 70 to start movement of the illuminationoptical system 30 and the observation optical system 40 when thebrightness (or, contrast or sharpness) of the images of thepredetermined site sequentially detected from the moving image by theanalyzing processor 211 becomes less than a predetermined thresholdvalue. In some other examples, the controller 200 (and the dataprocessor 210A) may be configured to control the movement mechanism 70to start movement of the illumination optical system 30 and theobservation optical system 40 when the color tone of the images of thepredetermined site sequentially detected from the moving image by theanalyzing processor 211 falls outside a predetermined allowable range.The threshold value and the range in the second condition may be fixedor variable. It should be noted that the second condition may be thesame as or different from the first condition.

As a result of this, the movement of the illumination optical system 30and the observation optical system 40 can be automatically started inresponse to deterioration in the image parameter, and then an optimumposition of the optical system can be searched. Therefore, it becomespossible to maintain the quality of the observation image. For example,the positional relationship between the subject's eye and the surgicalmicroscope 10 may change due to an eye movement or any other causes andthe image parameter may deteriorate after the optical system has beenplaced at an optimum position by automatic search. In such a case,according to the present aspect, the ophthalmic observation apparatus 1is capable of automatically detecting the deterioration in the imageparameter and then resuming the search for an optimum position of theoptical system. This makes it possible to achieve advantageous effectssuch as facilitation of ophthalmic observation.

The controller 200 (and the data processor 210A) may be configured todetermine a movement direction of the illumination optical system 30 andthe observation optical system 40 based on a change in the imageparameter. For example, the controller 200 (and the data processor 210A)determines whether or not a change in the image parameter caused bymovement of the illumination optical system 30 and the observationoptical system 40 in a certain direction is a favorable change. If thechange in the image parameter is determined to be a favorable change,then the controller 200 (and the data processor 210A) determines thisdirection (the above certain direction) as a movement direction. On theother hand, if the change in the image parameter is determined to be anunfavorable change, then the controller 200 (and the data processor210A) determines a direction other than this direction (the abovecertain direction), such as the direction opposite from this direction,as a movement direction. For example, the controller 200 (and the dataprocessor 210A) determines whether or not a change in the imageparameter caused by movement of the illumination optical system 30 andthe observation optical system 40 in a certain direction is a favorablechange. If the change in the image parameter is determined to be afavorable change, then the controller 200 (and the data processor 210A)determines this direction (the above certain direction) as a movementdirection. On the other hand, if the change in the image parameter isdetermined to be an unfavorable change, then the controller 200 (and thedata processor 210A) determines a direction other than this direction(the above certain direction), such as the direction opposite from thisdirection, as a movement direction. The controller 200 performs acontrol of the movement mechanism 70 based on the movement directiondetermined. As a specific example, if the brightness increases with themovement of the illumination optical system 30 and the observationoptical system 40 in a certain direction, then the controller 200 (andthe data processor 210A) can continue to move the illumination opticalsystem 30 and the observation optical system 40 in this direction. Ifthe brightness decreases with the movement in the certain direction, onthe other hand, the controller 200 (and the data processor 210A) canswitch the movement direction of the illumination optical system 30 andthe observation optical system 40 from the certain direction to theopposite direction therefrom.

With this, the ophthalmic observation apparatus 1 is capable ofautomatically determining a movement direction of the surgicalmicroscope 10 in accordance with a change in the image parameter, makingit possible to achieve advantageous effects such as facilitation ofophthalmic observation.

The processing performed by the controller 200 (and the data processor210A), that is, the control of the movement mechanism 70 based on achange in the image parameter, can be on and off (can be activated andinactivated). In other words, the ophthalmic observation apparatus 1 maybe configured to turn on and off this control function. For example, thecontrol function can be turned off in the case where automatic movementof the surgical microscope 10 (that is, movement of the surgicalmicroscope 10 at a timing unintended by the user) is desired to beavoided. The switching between activation and inactivation may beconducted through, for example, an operation using the operation device2 (e.g., foot switch). As another example, the ophthalmic observationapparatus 1 may be configured to switch between activation andinactivation by means of voice recognition technology or otherrecognition technology. In order to assist the user in such operationsand associated processing and works, the ophthalmic observationapparatus 1 may be provided with any of the following kinds of means: ameans of informing deterioration in the image parameter (e.g., adecrease in the brightness of a pupil image); a means of informing thestart of movement of the surgical microscope 10; a means of asking theuser for permission to move the surgical microscope 10, and so forth.

With such a configuration, the automatic movement function of thesurgical microscope 10 can be inactivated when, for example, the userdoes not want to use the automatic movement function or the user isconducting treatment on the subject's eye. In addition, such aconfiguration allows the ophthalmic observation apparatus 1 to informthat a predetermined condition, such as deterioration in the imageparameter, is satisfied. It should be noted that the method of informingmay be freely selected or determined. For example, the method ofinforming may be displaying of information on the display device 3,audio output, turning on of a light source, or other methods. Inaddition, the condition that triggers the informing (referred to as thethird condition) may be freely selected or determine. For example, thethird condition may be the same as or different from the first conditionand/or the second condition described above.

The ophthalmic observation apparatus 1 may be capable of accepting(receiving) a response from the user to the informing such as informingof deterioration in the image parameter. The response from the user isreceived by means of a predetermined device such as the operation device2 or a voice recognition device. Such a device is referred to as aresponse receiving unit. The controller 200 (and the data processor210A) may be configured to perform a control of the movement mechanism70 to move the illumination optical system 30 and the observationoptical system 40, based on the response from the user received by theresponse receiving unit.

With this, the ophthalmic observation apparatus 1 becomes capable ofautomatically detecting an event that the third condition has beensatisfied (e.g., that the image parameter has deteriorated), informingthat the third condition is satisfied, receiving a response from theuser to this informing, and moving the surgical microscope 10.Therefore, the user can become aware of that the third condition hasbeen satisfied and then issue an instruction to start the search for anoptimum position of the illumination optical system 30 and theobservation optical system 40.

The data processor 210B shown in FIG. 5 is an example of the dataprocessor 210 of FIG. 3 , and includes the determining processor 212 inaddition to the analyzing processor 211 of the data processor 210A inFIG. 4 . The data processor 210B is configured to be capable ofperforming the same or similar processing as or to the data processor210A.

The determining processor 212 is configured to perform determination ofwhether or not to execute processing performed by the controller 200(and the data processor 210B). Here, the processing performed by thecontroller 200 (and the data processor 2108) is the control of themovement mechanism 70 on the basis of a change in the image parameter.For example, the determining processor 212 is configured to perform thedetermination based on a moving image generated by the surgicalmicroscope 10. In some examples, the determining processor 212 may beconfigured to determine whether treatment is being performed on thesubject's eye based on the moving image generated by the surgicalmicroscope 10, and then to determine not to perform the control of themovement mechanism 70 on the basis of a change in the image parameter ifit has been determined that treatment is being performed on thesubject's eye. In this way, the ophthalmic observation apparatus 1 ofsome aspects may be provided with a means configured to analyze anobservation image obtained by the surgical microscope 10 and to executeautomatic determination of whether or not to move the surgicalmicroscope 10. In some examples, the ophthalmic observation apparatus 1may be configured to prohibit the movement of the surgical microscope 10while the user is conducting treatment on the subject's eye. Forexample, the ophthalmic observation apparatus 1 may be configured todetermine, by means of the determining processor 212, whether or not animage of an instrument (e.g., a surgical instrument) exists in theobservation image, and to execute a control to prohibit the movement ofthe surgical microscope 10 if it has been determined that an instrumentimage is depicted in the observation image. As another example, theophthalmic observation apparatus 1 may be configured to determine, bymeans of the determining processor 212, whether or not an image of aninstrument depicted in the observation image (moving image) is moving(that is, an instrument image changes with time), and to execute acontrol to prohibit the movement of the surgical microscope 10 if it hasbeen determined that an instrument image depicted in the observationimage has been moving.

With such a configuration, the ophthalmic observation apparatus 1 iscapable of carrying out automatic determination of whether or not toperform the automatic search for the position of the optical system ofthe surgical microscope 10. In addition, such a configuration allows theophthalmic observation apparatus 1 to prevent the surgical microscope 10from moving at a timing unintended (unexpected, undesired) by the user,such as while treatment is being performed on the subject's eye.

It is conceivable that the automatic search for the position of theoptical system of the surgical microscope 10 cannot yield an image ofgood quality. In order to address such a case, the ophthalmicobservation apparatus 1 may have the function described below (thefunction executed by the second controller). First, the ophthalmicobservation apparatus 1 (e.g., the data processor 210) finds an optimumvalue of the image parameter, for example, by performing a control ofthe movement mechanism 70 on the basis of a change in the imageparameter. Next, the ophthalmic observation apparatus 1 (e.g., the dataprocessor 210) determines whether or not this optimum value satisfiesthe fourth condition. When it has been determined that the optimum valueof the image parameter satisfies the fourth condition, the ophthalmicobservation apparatus 1 (e.g., the controller 200) performs at least oneof the following operations: an operation of outputting information(informing); an operation of increasing the amount of the illuminationlight given by the illumination optical system 30; an operation ofincreasing the gain of the image sensor of the observation opticalsystem 40; and an operation of changing a determination conditionregarding the image parameter. Several specific examples of thisfunction will be described. To begin with, the ophthalmic observationapparatus 1 performs moving image photography while moving theillumination optical system 30 and the observation optical system 40,and also, at the same time (in parallel, simultaneously), performssequential detection of the brightness value of pupil images, and thenobtains a maximum brightness value. This maximum brightness value is anexample of the optimum value of the image parameter. The maximumbrightness value is the maximum value among brightness values collectedby the search for the optimum position of the optical system. Next, theophthalmic observation apparatus 1 compares the maximum brightness valuewith the threshold value of the first condition described above, anddetermines whether the maximum brightness value is less than thisthreshold value. In the present example, the fourth condition isdetermined to be satisfied if the maximum brightness value is determinedto be less than the threshold value. When the maximum brightness valueis determined to be less than the threshold value, the ophthalmicobservation apparatus 1 may perform at least one of the operation ofinforming, the operation of increasing the illumination light amount bythe illumination optical system 30, the operation of increasing the gainof the image sensor of the observation optical system 40, and theoperation of changing the determination condition regarding the imageparameter. The informing operation is performed to inform the user thata pupil image (red reflex image, transillumination image) with asufficient brightness cannot be obtained by the automatic search for theposition of the optical system. Upon receipt of this information, theuser realizes the current state and is able to take desired measures.The operation of increasing the illumination light amount and theoperation of increasing the gain both contribute to an increase in thebrightness of the pupil image (red reflex image, transilluminationimage). The operation of changing the determination condition regardingthe image parameter may be designed, for example, to decrease thethreshold value of the first condition. In this case, it can be saidthat the continuation of medical practice (e.g., surgery) is givenpriority even if the brightness of the pupil image (red reflex image,transillumination image) is insufficient to a certain extent. Theophthalmic observation apparatus 1 may be configured to select one ormore operations from among the informing operation, the operation ofincreasing the illumination light amount, the operation of increasingthe gain, and the operation of changing the determination conditionregarding the image parameter, and then execute the operation selected.Furthermore, the ophthalmic observation apparatus 1 may be configured toperform, as a default operation, one or more of the informing operation,the operation of increasing the illumination light amount, the operationof increasing the gain, and the operation of changing the determinationcondition regarding the image parameter. In addition, the ophthalmicobservation apparatus 1 may be configured to perform a combination oftwo or more of the informing operation, the operation of increasing theillumination light amount, the operation of increasing the gain, and theoperation of changing the determination condition regarding the imageparameter. In some examples, if brightness equal to or greater than thethreshold value of the first condition has not been achieved by themovement of the illumination optical system 30 and the observationoptical system 40, the ophthalmic observation apparatus 1 first performsthe informing operation. This allows the user to be aware of the factthat the automatic search for the position of the optical system hasfailed to yield a red reflex image with sufficient brightness. Theophthalmic observation apparatus 1 then increases the amount of lightemitted by the light sources 31LA and 31RA, for example, upon receipt ofan instruction from the user or automatically. Then, the ophthalmicobservation apparatus 1 performs the automatic search for the positionof the optical system again. If the brightness of the red reflex imageis still insufficient even after the re-execution of the automaticsearch, the ophthalmic observation apparatus 1 then increases the gainsof the image sensors 62L and 62R of the observation optical system 40.Next, the ophthalmic observation apparatus 1 performs the automaticsearch for the position of the optical system once again. If thebrightness of the red reflex image is still insufficient even after thisautomatic search, the ophthalmic observation apparatus 1 decreases thethreshold value of the first condition by a predetermined value. Theophthalmic observation apparatus 1 then performs an automatic search forthe position of the optical system one more time. If the brightness ofthe red reflex image is still insufficient even after this automaticsearch, the ophthalmic observation apparatus 1 performs the informingoperation again. This informing operation is to notify the user that ared reflex image of sufficient brightness cannot be obtained by theseries of automatic search processes, and also to propose switching to amanual operation to the user. The manual operation may include, forexample, manual adjustment of the position of the illumination opticalsystem 30 and the observation optical system 40, manual adjustment ofthe illumination light amount, manual adjustment of the gain, and manualadjustment of the threshold value of the first condition.

In this way, the present example enables the ophthalmic observationapparatus 1 to take various kinds of suitable measures in the case whereperforming the automatic search for the position of the optical systemof the surgical microscope 10 does not produce an image of good quality.

When an image of good quality is obtained by the automatic search forthe position of the optical system of the surgical microscope 10 (inother words, when the automatic search has been successful), it is alsoconceivable that an image with the minimum necessary brightness may beobtained. In such a case, the illumination light amount may be decreasedin order to reduce the burden on the subject (this operation isperformed by the third controller). For example, after performing asuccessful automatic search for the position of the optical system, thecontroller 200 of the ophthalmic observation apparatus 1 decreases theillumination light amount by the illumination optical system 30 oncondition that the image parameter is included in a predetermined range.The predetermined range is, for example, a range equal to or greaterthan the threshold value of the first condition.

The present example makes it possible to reduce the burden on thesubject by decreasing the illumination light amount on condition that animage of good quality can be obtained, in the event of a successfulautomatic search for the position of the optical system of the surgicalmicroscope 10.

When a target site to be observed is the posterior eye segment, such aswhen performing posterior eye segment surgery, the ophthalmicobservation apparatus 1 may perform the same or similar processing as orto the above-described case of observing the anterior eye segment. Forexample, the ophthalmic observation apparatus 1 may be configured toperform the following processes: a process of performing movement of theillumination optical system 30 and the observation optical system 40 bythe movement mechanism 70 while generating a moving image by thesurgical microscope 10; a process of sequentially analyzing, by theanalyzing processor 211, a plurality of still images included in themoving image to sequentially detect images of a predetermined site ofthe posterior eye segment (e.g., optic nerve head); and a process ofcontrolling the movement mechanism 70 based on a change in apredetermined image parameter (e.g., brightness) of the imagessequentially detected. With this configuration, the same or similaractions and the same or similar advantageous effects as or to the caseof anterior eye segment observation can also be achieved in the case ofposterior eye segment observation. Any of the matters and itemsdescribed for the case of anterior eye segment observation can becombined with the case of posterior eye segment observation.

<Operation and Usage Mode>

The operation and the usage mode of the ophthalmic observation apparatus1 will be described. FIG. 6 shows an example of the operation and theusage mode of the ophthalmic observation apparatus 1. While the presentexample describes a case of coaxial illumination, the same or a similaroperation and the same or a similar usage mode can be implemented in thecases of other illumination methods (e.g., oblique illumination), in thecases of posterior eye segment observation, or in other cases.

(S1: Commence Generation and Display of Live Image with CoaxialIllumination)

To begin with, the user performs a predetermined operation using theoperation device 2 to select the coaxial illumination mode and cause theophthalmic observation apparatus 1 to start generating and displaying alive image of the subject's eye (the anterior eye segment thereof). Morespecifically, the surgical microscope 10 illuminates the subject's eyeby the illumination optical system 30 (the first illumination opticalsystems 31L and 31R), and at the same time (in parallel, simultaneously)generates digital image data (moving image, video) of the subject's eyeby the image sensors 62L and 62R. The generated moving image (the liveimage 301) is displayed in real time on the display device 3 (see FIG.7A). In other words, a moving image acquired by the surgical microscope10 is displayed on the display device 3 as a live image (as anobservation image). The user can conduct surgery while observing thelive image.

(S2: Detect Pupil Center from Live Image)

Next, the data processor 210 (e.g., the analyzing processor 211) detectsthe pupil center from the live image (frames thereof) whose generationhas started in the step S1. In some aspects, the data processor 210first applies image processing such as binarization and/or segmentationto detect the corneal ring 302 (see FIG. 7B). Note that the dataprocessor 210 may be configured to detect the pupil edge 303. In thecase of detecting the pupil edge 303, for example, the data processor210 may search for a low-brightness region corresponding to the pupil,move the low-brightness region to the central area of the frames, andthen apply approximation by an ellipse to the low-brightness region. Thedata processor 210 identifies the position (the pixel) 304 correspondingto the pupil center based on the corneal ring 302 detected (see FIG.7C). For example, the data processor 210 finds an approximate ellipse(or an approximate circle) of the detected corneal ring 302, and thenidentifies the center of this approximate ellipse. The identification ofthe center of the approximate ellipse may be performed, for example, byusing known geometrical methods.

(S3: Align the Optical Axis of Optical System with Pupil Center)

Next, the ophthalmic observation apparatus 1 aligns the optical axis ofthe surgical microscope 10 (the illumination optical system 30, theobservation optical system 40) with the pupil center 304 identified inthe step S2. For example, the ophthalmic observation apparatus 1performs the following processes: registration (position matching,position adjustment) between a newly acquired frame and the frame usedto detect the pupil center 304; identification of the positioncorresponding to the pupil center in the new frame based on the resultof the registration; and movement of the illumination optical system 30and the observation optical system 40 in such a manner that the opticalaxis of the surgical microscope is disposed at the positioncorresponding to the pupil center.

In some examples, the user can manually place the optical axis of thesurgical microscope 10 at the pupil center.

(S4: Detect Pupil Image)

The ophthalmic observation apparatus 1 (the analyzing processor 211)detects a pupil image from the live image after the optical axis of thesurgical microscope 10 has been placed at the pupil center 304 by thestep S3.

(S5: Calculate Brightness of Pupil Image)

Next, the ophthalmic observation apparatus 1 calculates the brightnessof the pupil image detected in the step S4. As the first example of thecalculation of the brightness of the pupil image, the data processor 210(e.g., the analyzing processor 211) performs the following processes: aprocess of dividing the pupil image (and its vicinity region) into aplurality of subregions; a process of determining a representative valueof the brightness of each subregion (the representative value may beaverage, maximum, mode, median, or any other statistical value); and aprocess of determining the brightness of the pupil image based on thedistribution of the representative values of brightness obtained for theplurality of subregions. The process of determining the brightness ofthe pupil image from the distribution may include any statisticalprocessing, such as calculation of the average, identification of themaximum, identification of the mode, or identification of the median. Asthe second example of the calculation of the brightness of the pupilimage, the data processor 210 (e.g., the analyzing processor 211) maydetermine the brightness of the pupil image based on the brightnessvalues of a plurality of pixels (all the pixels or a selected group ofpixels) of the pupil image using a predetermined statistical technique.

(S6: Is Brightness Equal to or Larger than Threshold Value and Maximum?)

Next, the ophthalmic observation apparatus 1 (the controller 200 or thedata processor 210) executes both determination of whether thebrightness of the pupil image calculated in the step S5 is equal to orlarger than a predetermined threshold value, and determination ofwhether the brightness of the pupil image is the maximum (localmaximum). It should be noted that the ophthalmic observation apparatus 1may be configured to perform only one of the two determinationprocesses. The threshold value determination (thresholding) is performedby comparing the brightness of the pupil image with the threshold value.This threshold value may be, for example, the threshold value of thefirst condition described above. The maximum determination is performedby monitoring the change in brightness caused by the movement of theillumination optical system 30 and the observation optical system 40.For example, by searching for a position at which the change inbrightness is switched from increasing to decreasing, it can bedetermined whether a certain position of the surgical microscope 10 (theillumination optical system 30 and the observation optical system 40) isthe position corresponding to maximum brightness (that is, the positionsof the illumination optical system 30 and the observation optical system40 where the brightness becomes the maximum can be found).

If it is determined that the brightness of the pupil image calculated inthe step S5 is equal to or larger than the threshold value and also thatthe brightness of the pupil image is the maximum (S6: Yes), theoperation proceeds to the step S8. If it is determined that thebrightness of the pupil image calculated in the step S5 is less than thethreshold value and/or that the brightness of the pupil image is not themaximum (S6: No), the operation proceeds to the step S7.

(S7: Move Optical System)

If the determination result “No” is issued in the step S6, theophthalmic observation apparatus 1 (the controller 200, the movementmechanism 70) moves the illumination optical system 30 and theobservation optical system 40. The movement direction may be freelyselected or determined, and may be any one or more of the verticaldirection (the Z direction), the horizontal direction (the X direction),and the front and back direction (the Y direction). Also, as describedabove, the movement direction may be determined based on the change inthe brightness. The movement amount (movement distance) may bedetermined in advance, or may be determined based on the change in thebrightness.

(S8: Complete Movement of Optical System)

If the determination result “Yes” is issued in the step S6, theophthalmic observation apparatus 1 (the controller 200) ends themovement of the illumination optical system 30 and the observationoptical system 40 (End). According to the present example of theoperation and the usage mode, the illumination optical system 30 and theobservation optical system 40 can be moved to and disposed at a positionwhere the brightness of the pupil image not only becomes equal to orlarger than the threshold value but also becomes maximized. In otherwords, the present example makes it possible to obtain a red refleximage that has the brightness equal to or larger than the thresholdvalue and that is of the maximum brightness.

Any of the matters and items described above can be combined with theoperation and the usage mode of the present example. For example, whenthe brightness of the pupil image falls below a predetermined value (thethreshold value of the second condition described above), the ophthalmicobservation apparatus 1 can move the illumination optical system 30 andthe observation optical system 40 again to search for a position wherethe brightness of the pupil image is maximized, and then move and placethe illumination optical system 30 and the observation optical system 40to and at the searched position. Furthermore, if the brightness equal toor larger than the threshold value cannot be achieved even after themovement of the illumination optical system 30 and the observationoptical system 40, the ophthalmic observation apparatus 1 may executeprocessing such as the operation of informing, the operation ofincreasing the illumination light amount, the operation of increasingthe gain of the image sensor, or the operation of reducing the thresholdvalue. In addition, after the illumination optical system 30 and theobservation optical system 40 are moved to a position where thebrightness of the pupil image is equal to or larger than the thresholdvalue and is the maximum, the illumination light amount may be decreasedwithin the range where the brightness of the pupil image is equal to orlarger than the predetermined value, thereby reducing the burden on thesubject.

<Method of Controlling Ophthalmic Observation Apparatus>

Some embodiment examples (e.g., the ophthalmic observation apparatus 1described above) provide a method of controlling an ophthalmicobservation apparatus. It is possible to combine any items or mattersrelating to the ophthalmic observation apparatus 1 of the aboveembodiment examples with the example of the method described below.

An ophthalmic observation apparatus controlled by the method of anaspect example includes an optical system for observing a subject's eye(e.g., the illumination optical system 30 and the observation opticalsystem 40 moved by the movement mechanism 70) and a processor (e.g., thecontroller 200 and the data processor 210). The method of the presentaspect example first causes the ophthalmic observation apparatus toperform movement of the optical system and generation of a moving imageof the subject's eye by the optical system in parallel. Further, themethod of the present aspect example causes the processor tosequentially analyze a plurality of still images included in the movingimage to sequentially detect images of a predetermined site of thesubject's eye. In addition, the method of the present aspect examplecauses the processor to perform movement of the optical system based ona change in a predetermined image parameter of the images of thepredetermined site sequentially detected.

The method of the present aspect example is capable of achieving thesame actions and effects as those of the ophthalmic observationapparatus 1 of the above embodiment examples. In addition, by combiningany of the matters and items relating to the ophthalmic observationapparatus 1 of the above embodiment examples with the method of thepresent aspect example, the resulting method becomes capable ofachieving the actions and effects corresponding to the combined mattersand/or items.

<Program>

Some embodiment examples provide a program causing a computer to executethe method of the aspect example described above. It is possible tocombine any of the matters and items relating to the ophthalmicobservation apparatus 1 of the above embodiment examples with such aprogram.

The program thus configured is capable of achieving the same actions andeffects as those of the ophthalmic observation apparatus 1 of the aboveembodiment examples. In addition, by combining any of the matters anditems relating to the ophthalmic observation apparatus 1 of the aboveembodiment examples with the program, the resulting program is capableof achieving the actions and effects corresponding to the combinedmatters and/or items.

<Recording Medium>

Some embodiment examples provide a computer-readable non-transitoryrecording medium storing the program described above. It is possible tocombine any of the matters and items relating to the ophthalmicobservation apparatus 1 of the above embodiment examples with such arecording medium. The non-transitory recording medium may be in anyform, and examples thereof include magnetic disks, optical disks,magneto-optical disks, and semiconductor memories.

The recording medium thus configured is capable of achieving the sameactions and effects as those of the ophthalmic observation apparatus 1of the above embodiment examples. In addition, by combining any of thematters and items relating to the ophthalmic observation apparatus 1 ofthe above embodiment examples with the recording medium, the resultingrecording medium is capable of achieving the actions and effectscorresponding to the combined matters and/or items.

The present disclosure can perform automatic optimization of observationenvironment by automatically determining the position where returnintensity of fundus reflection of coaxial illumination is appropriate(equal to or larger than a threshold value, maximized) and moving themicroscope optical system, for example. In addition, the presentdisclosure can maintain good observation environment by performing thesame or a similar operation when the subject or the subject's eye moves.Furthermore, the same or a similar operation may be performed in thecases of employing an illumination method other than coaxialillumination (e.g., oblique illumination). For example, if a user'spreference is taken into consideration, preset information may beprepared for each user.

In addition, the present disclosure allows the user to always observethe eye under optimal illumination conditions, as long as the operationaccording to the present disclosure is functioning properly. As a resultof this, the success rate of surgery can be improved, the operation timecan be shortened, and the amount of illumination can be reduced. Theseeffects reduce the burden on the patient. For example, by employing thepresent disclosure in cataract surgery, an appropriate red reflex imagecan be obtained with coaxial illumination, which makes it possible toachieve appropriate and efficient works such as phacoemulsification(crystalline lens emulsification and aspiration) works and posteriorcapsule polishing works.

The embodiments described in the present disclosure are merely examples,and any modification, omission, addition, substitution, etc. can be madewithin the scope of the present disclosure and its equivalents.

EXPLANATION OF REFERENCE CHARACTERS

-   -   1 Ophthalmic observation apparatus    -   2 Operation device    -   3 Display device    -   10 Surgical microscope    -   30 Illumination optical system    -   40 Observation optical system    -   200 Controller    -   210 Data processor    -   211 Analyzing processor    -   212 Determining processor

1. An ophthalmic observation apparatus for observing a subject's eye,comprising: a surgical microscope configured to generate a moving imageby illuminating and photographing the subject's eye; a movementmechanism configured to move the surgical microscope; an analyzingprocessor configured to sequentially analyze a plurality of still imagesincluded in the moving image generated by the surgical microscope beingmoved by the movement mechanism to sequentially detect images of apredetermined site of the subject's eye; and a first controller circuitconfigured to control the movement mechanism based on a change in apredetermined image parameter of the images sequentially detected by theanalyzing processor.
 2. The ophthalmic observation apparatus accordingto claim 1, wherein the first controller circuit is configured tocontrol the movement mechanism to stop movement of the surgicalmicroscope when the image parameter of the images sequentially detectedby the analyzing processor satisfies a first condition.
 3. Theophthalmic observation apparatus according to claim 2, wherein the imageparameter includes brightness, and the first condition includes at leastone of a condition that the brightness is maximum and a condition thatthe brightness is equal to or larger than a first threshold value. 4.The ophthalmic observation apparatus according to claim 1, wherein thefirst controller circuit is configured to control the movement mechanismto start movement of the surgical microscope when the image parameter ofthe images sequentially detected by the analyzing processor satisfies asecond condition.
 5. The ophthalmic observation apparatus according toclaim 4, wherein the image parameter includes brightness, and the secondcondition includes a condition that the brightness is smaller than asecond threshold value.
 6. The ophthalmic observation apparatusaccording to claim 1, wherein the first controller circuit is configuredto determine a movement direction of the surgical microscope based onthe change in the image parameter and perform a control of the movementmechanism based on the movement direction determined.
 7. The ophthalmicobservation apparatus according to claim 1, wherein the surgicalmicroscope is configured to generate a moving image of an anterior eyesegment of the subject's eye, and the predetermined site includes apupil.
 8. The ophthalmic observation apparatus according to claim 1,wherein the surgical microscope is configured to generate a moving imageof a posterior eye segment of the subject's eye, and the predeterminedsite includes an optic nerve head.
 9. The ophthalmic observationapparatus according to claim 1, wherein the control of the movementmechanism based on the change in the image parameter performed by thefirst controller circuit can be activated and inactivated.
 10. Theophthalmic observation apparatus according to claim 1, furthercomprising an informing unit configured to perform informing when theimage parameter of the images sequentially detected by the analyzingprocessor satisfies a third condition.
 11. The ophthalmic observationapparatus according to claim 10, further comprising a response receivingunit that includes a user operation device or a voice recognition deviceconfigured to receive a response of the user to the informing, whereinthe first controller circuit is configured to perform a control of themovement mechanism based on the response received by the responsereceiving unit.
 12. The ophthalmic observation apparatus according toclaim 1, further comprising a determining processor configured toperform determination of whether or not to perform the control of themovement mechanism based on the change in the image parameter performedby the first controller circuit.
 13. The ophthalmic observationapparatus according to claim 12, wherein the determining processor isconfigured to perform the determination based on the moving imagegenerated by the surgical microscope.
 14. The ophthalmic observationapparatus according to claim 13, wherein the determining processor isconfigured to determine whether or not a treatment on the subject's eyeis being performed based on the moving image generated by the surgicalmicroscope, and determine not to perform the control of the movementmechanism when it is determined that the treatment is being performed.15. The ophthalmic observation apparatus according to claim 1, furthercomprising a second controller circuit configured to perform at leastone of informing, increasing in an illumination light amount by thesurgical microscope, increasing in a gain of an image sensor of thesurgical microscope, and changing of a determination condition regardingthe image parameter when an optimum value of the image parameteracquired during the control of the movement mechanism based on thechange in the image parameter satisfies a fourth condition.
 16. Theophthalmic observation apparatus according to claim 1, furthercomprising a third controller circuit configured to decrease anillumination light amount by the surgical microscope on condition thatthe image parameter is included in a predetermined range after thecontrol of the movement mechanism based on the change in the imageparameter.
 17. The ophthalmic observation apparatus according to claim1, wherein the image parameter includes at least one of brightness,contrast, sharpness, and color tone.
 18. A method of controlling anophthalmic observation apparatus including an optical system forobserving a subject's eye and a processor, the method comprising:causing the ophthalmic observation apparatus to perform movement of theoptical system and generation of a moving image of the subject's eye bythe optical system in parallel; causing the processor to sequentiallyanalyze a plurality of still images included in the moving image tosequentially detect images of a predetermined site of the subject's eye;and causing the processor to perform movement of the optical systembased on a change in a predetermined image parameter of the imagessequentially detected.
 19. A computer-readable non-transitory recordingmedium storing a program configured to cause a computer to execute themethod of claim
 18. 20. (canceled)
 21. The ophthalmic observationapparatus according to claim 10, wherein the informing unit includes atleast one of a display device, an audio output device, and a lightsource.